Quantitative HLA‐class‐II/factor VIII (FVIII) peptidomic variation in dendritic cells correlates with the immunogenic potential of therapeutic FVIII proteins in hemophilia A

Abstract

BackgroundPlasma‐derived (pd) or recombinant (r) therapeutic factor VIII proteins (FVIIIs) are infused to arrest/prevent bleeding in patients with hemophilia A (PWHA). However, FVIIIs are neutralized if anti‐FVIII‐antibodies (inhibitors) develop. Accumulating evidence suggests that pdFVIIIs with von Willebrand factor (VWF) are less immunogenic than rFVIIIs and that distinct rFVIIIs are differentially immunogenic. Since inhibitor development is T‐helper‐cell‐dependent, human leukocyte antigen (HLA)‐class‐II (HLAcII) molecules constitute an important early determinant. ObjectivesUse dendritic cell (DC)‐protein processing/presentation assays with mass‐spectrometric and peptide‐proteomic analyses to quantify the DP‐bound, DQ‐bound, and DR‐bound FVIII‐derived peptides in individual HLAcII repertoires and compare the immunogenic potential of six distinct FVIIIs based on their measured peptide counts. Patients/MethodsMonocyte‐derived DCs from normal donors and/or PWHA were cultured with either: Mix‐rFVIII, a VWF‐free equimolar mixture of a full‐length (FL)‐rFVIII [Advate® (Takeda)] and four distinct B‐domain‐deleted (BDD)‐rFVIIIs [Xyntha® (Pfizer), NovoEight® (Novo‐Nordisk), Nuwiq® (Octapharma), and Afstyla® (CSL Behring GmBH)]; a pdFVIII + pdVWF [Beriate® (CSL Behring GmBH)]; Advate ± pdVWF; Afstyla ± pdVWF; and Xyntha + pdVWF. ResultsWe showed that (i) Beriate had a significantly lower immunogenic potential than Advate ± pdVWF, Afstyla − pdVWF, and Mix‐rFVIII; (ii) distinct FVIIIs differed significantly in their immunogenic potential in that, in addition to (i), Afstyla + pdVWF had a significantly lower immunogenic potential than Beriate, while the immunogenic potential of Beriate was not significantly different from that of Xyntha + pdVWF; and (iii) rFVIIIs with pdVWF had significantly lower immunogenic potentials than the same rFVIIIs without pdVWF. ConclusionsOur results provide HLAcII peptidomic level explanations for several important clinical observations/issues including the differential immunogenicity of distinct FVIIIs and the role of HLAcII genetics in inhibitor development.